The essential characteristics of face-to-face meetings can be simulated by multimedia conferencing systems. Such conferencing systems permit separated conference participants to communicate with one another in multiple media such as voice, video, and data from their own work places without requiring that they actually convene in the same place.
In one prior approach, these conferencing systems involve a plurality of complicated and expensive computer workstations connected together by transmission facilities which act merely as a transport mechanism for whatever is to be communicated between the workstations. There are significant problems with such a distributed architecture which are preventing this approach from becoming a widespread commercially viable reality. Each of the workstations in these prior distributed environments contains a large amount of the multimedia data processing capabilities, including the necessary bridging and synchronization circuits, used to effectuate a conference between meeting participants. This increases the cost to each potential multimedia user which usually places multimedia communications beyond that user's interest or financial means. In addition, prior localized desktop applications make it difficult to achieve long-term flexible multimedia conferencing environments conveniently because at least one of the workstations must stay up at all times during the required life of the conference environment. There is no way convenient for all the conferees to leave the conference and then easily return and pick up the conference where it left off. It also is difficult to synchronize the various parts of a multimedia conference for proper presentation to the meeting participants in a distributed environment. In this situation, it is difficult to create multimedia connections between disparate communications equipment, for example, two computers running different operating systems.
In addition to the distributed architectures described above, there are some centralized architectures involving media bridges located in the network rather than in local workstations. For example, the AT&T long distance network contains some audio and video bridging capability such as the bridging involved in the AT&T Alliance teleconferencing service and the AT&T Global Business Video Conferencing Services. Although these services are useful telecommunication services, Applicants have identified significant areas which might be improved. Applicants have appreciated that it is difficult to achieve flexible, long term multimedia conferences between a variable number of users having different media capabilities. Synchronous modes of communications, such as telephone calls, and asynchronous modes of communications, such as electronic mail, are not easily merged in the prior multimedia communications systems. The prior multimedia communications systems also make it difficult to integrate disparate communications equipment possessed by various conferees into an effective multimedia conference. It is difficult for conferees having different levels of multimedia communications capabilities to enter and leave a given multimedia conference freely. There is no convenient way to effectuate multimedia communications between many potential users such as those who might be connected together by way of a complicated network, such as an extensive local area network or a wide area network such as a public telephone network. For example, there is no way for a telecommunications carrier to provide a multimedia communications service to a wide range of its telephone customers using the present multimedia conferencing systems.